1. Summary of Invention
The present invention relates generally to fluid seals, and more particularly to an oil seal adapted to be fitted in a housing, such as a crank shaft seal within an engine cover.
2. Background of the Invention
It has long been known in the art to use a separate seal member between a cylindrical member such as a crank shaft and a housing containing a liquid environment to maintain a fluid type seal at the point where the cylindrical object extends through the housing. This seal arrangement can be used for a reciprocating piston or for a rotating shaft, and has applications in hydraulic devices and in oil or liquid cooled engines including, as here, automotive engines. The primary design concerns for such seals are fluid tightness, durability, cost and weight. The cost of the seal has become an increasingly important factor, particularly in the automotive industry. There are many factors that affect the cost of the seals, including materials used, the amount of materials used, and the machining or production costs. Further, there are the associated costs in preparing the bore of the housing for receiving the seal. While the weights of the seal and the housing are related to the cost, there is also an important consideration from the standpoint of overall design, particularly in the automotive industry.
One critical design consideration in seal effectiveness is the retention force holding the seal within the housing so that the seal is held without axial or circumferential movement. Such axial or circumferential movement adversely affects the sealing engagement between the seal and the housing. The retention force also directly relates to the durability of the seal. Certain prior art patents have been directed to methods of securing a seal within the housing. U.S. Pat. No. 4,747,603 to Sugino teaches the use of a nitrided metallic reinforcement ring, but the nitriding process is more costly. The nitriding process also increases the installation loads required to install the seal into the housing, which increases the installation time and increases the possibility of installation error or installation damage to the seal or housing U.S. Pat. No 4,560,177 to Riley shows a snap-ring retention device, but requires a wider bore to house the snap ring and requires an added component, the snap ring, which increases the overall system cost. U.K. Patent No. 2,215,786 to Mims teaches a secondary process of sonically welding the seal into the bore, but the secondary process adds cost, and if a replacement seal is required, both the seal and the bore of the housing must be replaced which increases the repair cost. U.S. Pat. No. 2,889,163 to Stephens requires an adhesive to be applied to the seal to bond the seal to the bore of the housing, but requires the additional cost of the adhesive and additional labor cost for applying the adhesive. Further, the labor costs in the Stephens device are increased because the adhesive must be applied carefully in order to be effective, excessive adhesive can extrude onto the seal lip and interfere with the sealing function, whereas too little adhesive may allow for inadequate retention forces. U.S. Pat. No. 4,484,751 to Deuring involves the direct bonding of the sealing lip to the bore of the housing, which requires extensive preparation of the bore for the bonding process and which is difficult to perform at high production rates because of the difficulty in fitting large carriers and covers into mold cavities. Further, if a replacement seal is required, both the seal and the bore must be replaced, increasing the repair cost.
Other attempts to secure the seal within the bore of the housing include U.S. Pat. No. 4,026,563 to Bainard which requires the machining of the groove in the bore diameter of the housing to receive and lock a rib of the seal. This groove is continuous and thus only retains the seal in an axial direction and not in a circumferential direction (rotation). Further, the continuous groove could not be molded in a unitary bore or housing but instead requires a machining or secondary process which increases the cost of preparing the bore of the housing. A similar type of circumferential groove and rib configuration for the bore and seal respectively is shown in U.S. Pat. No. 2,834,616 to Gebert.
Wherefore, it is an objective of the present invention to provide a seal and housing assembly in which the seal is securely retained axially and circumferentially, in which the seal and housing member are as lightweight as possible, and in which the seal and housing are as easily and efficiently produced or manufactured as possible.
It is a further object of the present invention to provide a seal which is securely retained axially and circumferentially but which requires as little installation force as possible and which can be effectively and efficiently repaired or replaced.
It is a further object of the present invention to provide a method of manufacturing a housing for receiving a seal such as a shaft seal which is simply molded or cast and which allows de-flashing without affecting the seal bore sealing area.
3. Summary of the Present Invention
An oil seal, and in combination therewith a housing having a bore with a non-continuous groove. The oil seal has a locking or retention rib held within the non-continuous groove and a second sealing rib in compression fit against the sealing surface of the bore.